tests/docker: Fix microblaze atomics

tests/docker: Fix microblaze atomics

GCC produces invalid code for microblaze atomics.

The fix is unfortunately not upstream, so fetch it from an external
location and apply it locally.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Message-Id: <20240919152308.10440-1-iii@linux.ibm.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20241023113406.1284676-2-alex.bennee@linaro.org>